1. Field of the Invention
The present invention relates to an air conditioner, and more particularly, to a serial data communication device of an air conditioner which is capable of executing a serial data communication by using an alternating current power line between an indoor microprocessor and an outdoor microprocessor.
2. Discussion of Related Art
Generally, an air conditioner is comprised of an indoor heat exchanger and an outdoor heat exchanger. In the air conditioner, typically, an indoor device is occupied on the interior of space in which air conditioning and dehumidification are needed and an outdoor device is occupied on the outside of the above space. For example, in case of house or building, the area in which the air conditioner is to be installed is firstly divided into an indoor area in which a human body dwells and an outdoor area.
Such the air conditioner includes a compressor which serves to compress refrigerant, an outdoor heat exchange which expands the refrigerant within a passage, a capillary tube which functions to reduce the pressure of refrigerant within the compressor, and an indoor heat exchanger to which an indoor fan is attached, each of which is connected by a pipe line.
FIG. 1 is a circuit diagram illustrating a serial data communication device of an air conditioner in the prior art. Referring to FIG. 1, the conventional communication device connects an indoor microprocessor 50 with an outdoor microprocessor 10 by means of a connector CNT1, thus to achieve the communication between the indoor/outdoor microprocessors and to accomplish the supply of an alternating current power to the outdoor microprocessor 10.
In more detail, terminals C and D of the connector CNT1 serve to supply the alternating current power to the outdoor microprocessor 10, and terminals A and B of the connector CNT1 forms a communication line between the indoor microprocessor 50 and the outdoor microprocessor 10, to thereby achieve a serial data communication therebetween.
A data transmission process from the indoor microprocessor 50 to the outdoor microprocessor 10 will be firstly discussed.
In the case where data transmission of the indoor microprocessor 50 to the outdoor microprocessor 10 is performed, a data receiving terminal RXD1 of the indoor microprocessor 50 is in a disabled state, and then a data transmitting terminal TXD1 of the indoor microprocessor 50 outputs the data to be transmitted to the outdoor microprocessor 10.
Next, a first comparator COMP1 compares an output voltage waveform with a reference voltage waveform which is adjusted by resistors R2 and R3, to thereby output the compared result to the terminal A of the connector CNT1 through an output resistor R9 and a pull-up resistor R10.
Then, the transmission data on the data transmitting terminal TXD1 of the indoor microprocessor 50 is transmitted through a first photocoupler PC1. Thereafter, the transmission data is passed through a pull-up resistor R12 and a load resistor R13, to prevent the generation of noise therein, and is then transmitted to a data receiving terminal RXD2 of the outdoor microprocessor 10.
Secondly, in the case where data transmission of the outdoor microprocessor 10 to the indoor microprocessor 50 is performed, the data receiving terminal RXD2 of the outdoor microprocessor 10 is in a disabled state, and then a data transmitting terminal TXD2 of the outdoor microprocessor 10 outputs the data to be transmitted to the indoor microprocessor 50. Then, the data outputted from the data transmitting terminal TXD2 is transmitted through a second photocoupler PC2 and is finally applied to an input terminal of a second comparator COMP2 through resistors R14, R9 and R7 and a pull-up resistor R10.
Next, the second comparator COMP2 compares the output voltage level of the data transmitted from the outdoor microprocessor 10 with the reference voltage level to thereby output the compared result to the data receiving terminal RXD1 of the indoor microprocessor 50, thus to achieve a desired data communication between the indoor microprocessor 50 and the outdoor microprocessor 10.
A reference numeral R4 denotes a load resistor, R5 a pull-up resistor, each of R5 and R8 a divisional pressure resistor, and R16 a protection resistor of a light emitting diode LED1. Further, each of reference numerals C1, C2 and C3 represents a noise removing condenser.
However, the conventional serial data communication device in an air conditioner should require two power lines for supplying an alternating current power and two communication lines for exchanging data, such that there is a problem in that the disconnection between the alternating current power lines and the communication lines may be generated, which results in the damage of peripheral circuits thereof, unfortunately.
Moreover, the conventional serial data communication device in an air conditioner should have a single connector in which the alternating power lines and the communication lines are all formed, such that there is a problem in that noises in data during the data transmission may be generated.